For decades, beta-carotene, a carotenoid present in many green and yellow vegetables, was used to treat beta-carotene and vitamin A deficiencies in mammals. Recently, beta-carotene has been reported to have many important biological functions in addition to its role as a vitamin A precursor. For example, beta-carotene has been shown to have broad anti-cancer (Krinsky, 1990Iftikhar et al. 1996) and anti-toxic effects (Martin et al. 1996Baranowitz & Maderson, 1993,1995,1997). More specifically, it has been reported to protect mammalian cells against cytotoxicity and genotoxicity in both in vivo and in vitro experimental model systems (Krinsky et al., 1993).
Various epidemiological studies have also suggested that high beta-carotene intake may reduce the incidence of a number of life-threatening diseases, such as cancer (Krinsky, N. I. et al. eds., 1989 in Carotenoids Chemistry and Biology, Plenham Press, New York). Beta-carotene has also been reported to effectively treat the most common cause of blindness in the U.S., age-related macular degeneration (Baranowitz & Brookner, 1994, 1995). The protective effects of beta-carotene may be attributed to the ability of beta-carotene to quench a variety of free radical species (Foote et al., 1970).
A major drawback of the use of beta-carotene for the treatment of various diseases is that the beta-carotene molecule is highly lipophilic and therefore poorly taken up by most animals (Wamer et al., (1985) Nutr. Rep. Int., 32, 295-301) and cell-lines in culture (Renner et al., (1985) Mutat. Res. 144, 251-256). In order to optimize delivery of beta-carotene, researchers have investigated a variety of drug delivery vehicles in an attempt to increase beta-carotene's bioavailibility in animal tissues but have had little success. Dimethylsulfoxide, for instance, was not found to be a suitable vehicle for incorporating high carotenoid concentrations (Craft, 1992; Gross et al. 1997).
Therefore, there is a need for a method for administering high concentrations of beta-carotene with low toxicity and high tolerability. Such a method would preferably be simple to administer and use relatively inexpensive materials.